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Given that we want to make the most out of our time spent exercising, the question of what time is best to exercise if we want to maximise our results is one that is frequently asked and yet is still one that many of us feels remains unanswered. At a superficial, and entirely practical level, the best time to exercise is 'when you can', but if we scratch the surface and delve a little deeper, when should we time our exercise if we want the most bang for our buck?

For many of us there is a time of day that we feel more, or less, energised and we prefer to leverage this and exercise at that time, because it is the time in our daily cycle, or circadian rhythm as it as referred to, when we are at our most alert and feel most motivated. These circadian rhythms or biological clocks govern how nearly every organism functions and are largely in-built and sustained, but they are also susceptible to change and can be adjusted via the influence of external factors that stimulate us, in particular light, for example.

The research is varied, and sometimes contradictory, but we typically exhibit certain cognitive traits and have increased or decreased hormonal outputs at certain times throughout the day. In a properly functioning system, we should have the most acute raise in blood pressure first thing in the morning and should secrete stress hormones, such as cortisol, from waking until broadly mid-morning, the times during the day when we need to be at our most alert and active. These stress hormones should then continue to secrete throughout the day, dipping in the evening in readiness for sleep and restful repair.

In opposition to our stress hormones, which keep us alert and 'switched on', are those responsible for sleep, growth and repair. Melatonin for example, the hormone that regulates our sleep-wake-cycles, starts to secrete at circa 9pm making us feel relaxed and drowsy, priming us for an essential nights sleep and restful recovery. Melatonin should stay elevated while we sleep, then dropping in the morning after we wake, when our stress hormones kick us into gear.

Given that how and when our body functions at certain times of day is regulated by our own internal clock, which is both inherited and learned, it makes sense that we are all going to be on our 'own time'. Some people describe themselves as 'night owls' or, at the other end, 'morning people', which we can only assume means that their hormonal environments are different at any given time, hence their contrasting energy levels and feelings of alertness. Based on the fact that exposure to light can be a factor that influences our body clock, it would be reasonable to assume that those of us who watch television and check our tablets late at night will adopt different sleep patterns to those who dim the light and meditate at 9pm.

In terms of how this affects when we should exercise to optimise the benefits, it is likely to be highly individual. All things being equal, it might be a fair assumption that mid-morning, when circulating stress hormones should be elevated and we are at our most alert, might be the best time to workout. In contrast, exercise later in the evening, when our stress hormones should start to decline in favor of our sleep and repair hormones, might be the least favorable time to hit the gym. However, given that our biological clocks are susceptible to change via exposure to external factors, some of us may have adapted, and mid-morning might no longer suit us.

However, as with anything, there is optimal and there is what is most doable. For many of us, a mid-morning training session is not practical and it is a straight choice between working out first thing in the morning or going after work. For me personally, I'm always better first thing in the morning. It effects my sleep if I exercise in the evening, plus I am more alert first thing when I haven't been mentally distracted by the day. I have also been going to bed before 10pm and getting up early for several years, so perhaps my body clock has adapted accordingly.